Azithromycin changed airway bacteria but didn’t lower inflammation

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Key Takeaway

Giving azithromycin to people hospitalized with COVID-19 changed the bacteria and antibiotic resistance in the nose and throat but did not reduce inflammation or help the body's immune response.

What They Found

Researchers studied nasal swabs from over 1,100 patients hospitalized with COVID-19 and compared those who got azithromycin to those who got no antibiotics or other antibiotics. Within one day of azithromycin treatment, the mix of microbes in the upper airway (nose and throat) shifted — like rearranging the kinds of plants in a garden. Azithromycin increased the activity and proportion of specific antibiotic-resistance genes (called MLS resistance genes), and these changes lasted more than a week. The rise in resistance genes was linked to both harmless bacteria and bacteria that can cause infections, meaning the change wasn’t limited to one type of microbe. The treatment did not lower signs of inflammation in the blood or airways, so it did not show the expected anti-inflammatory benefit in these patients.

Who Should Care and Why

People with MS and their caregivers should care because many people with MS take immune-modifying medicines or face infections where antibiotics might be considered; changing the airway bacteria and increasing resistance can affect future infections and treatment choices. Think of the airway microbiome like a neighborhood: giving azithromycin can change which neighbors live there and make some of them better at resisting certain medicines. Caregivers and MS patients should know that using azithromycin when it may not help inflammation could still make future infections harder to treat. Neurologists, primary doctors, and infection specialists should consider this when deciding whether to give azithromycin for viral respiratory illness, especially in people whose immune systems are altered by MS treatments. In daily life, this means asking whether an antibiotic is really needed for a viral illness and discussing risks and benefits with your care team.

Important Considerations

This study looked at hospitalized COVID-19 patients, so results may not be exactly the same for milder infections or for people with MS who are not hospitalized. The study shows changes in bacteria and resistance genes and no decrease in measured inflammation, but it did not directly measure whether these microbiome changes caused more infections later on. Because this is observational, doctors should use these findings together with clinical judgment and other evidence when deciding on antibiotics.

AI-generated summary — for informational purposes only, not medical advice

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Treatment Updates Early Research Clinical Trials

Whether you’ve recently been diagnosed with Multiple Sclerosis (MS) or are seeking to broaden your understanding of this complex, neurodegenerative disease, navigating the latest research can feel overwhelming. Studies published in respected medical journals like Nature microbiology often range from early-stage, exploratory work to advanced clinical trials. These evidence-based findings help shape new disease-modifying therapies, guide symptom management techniques, and deepen our knowledge of MS progression.

However, not all research is created equal. Some clinical research studies may have smaller sample sizes, evolving methodologies, or limitations that warrant careful interpretation. For a more comprehensive, accurate understanding, we recommend reviewing the original source material—accessible via the More Details section above—and consulting with healthcare professionals who specialize in MS care.

By presenting a wide range of MS-focused studies—spanning cutting-edge treatments, emerging therapies, and established best practices—we aim to empower patients, caregivers, and clinicians to stay informed and make well-informed decisions when managing Multiple Sclerosis.

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